1. Field
The present disclosure relates to zoom lens systems, interchangeable lens apparatuses, and camera systems.
2. Description of the Related Art
In recent years, interchangeable-lens type digital camera systems (also referred to simply as “camera systems”, hereinafter) have been spreading rapidly. Such interchangeable-lens type digital camera systems realize: taking of high-sensitive and high-quality images; high-speed focusing and high-speed image processing after image taking; and easy replacement of an interchangeable lens apparatus in accordance with a desired scene. Meanwhile, an interchangeable lens apparatus having a zoom lens system that forms an optical image with variable magnification is popular because it allows free change of focal length without the necessity of lens replacement.
Japanese Laid-Open Patent Publication No. 2011-232543 discloses a zoom lens having a five-unit configuration of positive, negative, positive, negative, and positive, in which air spaces between first to third lens units are varied to change magnification, and a lens unit provided on an image side relative to an aperture diaphragm moves along an optical axis at the time of focusing.
Japanese Laid-Open Patent Publication No. 2000-214386 discloses a zoom lens having a long back focal length, and a five-unit configuration of positive, negative, negative, positive, and positive, in which image blur compensation is performed by using a lens unit comprising the entirety or part of a fourth lens unit.
Japanese Laid-Open Patent Publication No. 2012-194279 discloses a zoom lens having a five-unit configuration of positive, negative, positive, positive, and positive, in which, at the time of magnification change, a first lens unit moves to an object side so as to be apart from a second lens unit, a third lens unit moves to the object side so as to be close to the second lens unit, and a fourth lens unit moves to the object side so as to be close to the third lens unit.
Japanese Laid-Open Patent Publication No. 10-221600 discloses a zoom lens having a four-unit configuration of positive, negative, positive, and negative, in which, in a close-object in-focus condition, a first lens unit is moved to an object side, a third lens unit is moved to the object side, and a fourth lens unit is moved to an image side.
Japanese Laid-Open Patent Publication No. 2009-163102 discloses a zoom lens having a four-unit configuration of positive, negative, positive, and negative, and including an aperture diaphragm between a most image side lens surface of a second lens unit and a most image side lens surface of a third lens unit.